BIBLIOGRAFÍA

LPRF

In the severely resorbed posterior mandible, the placement of dental implants in ideal position is often compromised by the significant post-extraction centrifuge alveolar bone resorption. The shape of the residual alveolar ridges and the residual bone height above the inferior alveolar nerve often make the area not suitable for direct implantation. Even if the use of short implants offers excellent results when the residual bone volumes are high and wide enough to receive these implants [1], there is no other solution than bone regeneration surgery prior to implant placement when the alveolar ridges are very thin [2]. However bone regeneration itself remains a challenge in this area, as the mandibular posterior residual alveolar ridges are always very cortical with a low vascularization and therefore not really adapted to the integration of bone grafting material or regeneration of bone cavities. Finally, the posterior mandible is a place of significant mechanical constraints applied on the bone and gingival tissues during the mastication function, and this can compromise the healing of a bone regeneration chamber, particularly through the risk of soft tissue dehiscence after the regeneration surgery.

The topical use of platelet concentrates is recent and its efficiency remains controversial. Several techniques for platelet concentrates are available; however, their applications have been confusing because each method leads to a different product with different biology and potential uses. Here, we present classification of the different platelet concentrates into four categories, depending on their leucocyte and fibrin content: pure platelet-rich plasma (P-PRP), such as cell separator PRP, Vivostat PRF or Anitua’s PRGF; leucocyte- and platelet-rich plasma (L-PRP), such as Curasan, Regen, Plateltex, SmartPReP, PCCS, Magellan or GPS PRP; pure plaletet- rich fibrin (P-PRF), such as Fibrinet; and leucocyteand platelet-rich fibrin (L-PRF), such as Choukroun’s PRF. This classification should help to elucidate successes and failures that have occurred so far, as well as providing an objective approach for the further development of these techniques.

David M. Dohan Ehrenfest, Lars Rasmusson and Tomas Albrektsson Department of Biomaterials, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, Sweden

Objectives: Platelet-rich fibrin (PRF)-based membranes have been used for covering alveolar ridge augmentation side in several in vivo studies. Few in vitro studies on PRF and no studies using human periosteal cells for tissue engineering have been published. The aim is a comparison of PRF with the commonly used collagen membrane Bio-Gides as scaffolds for periosteal tissue engineering.

Material and methods: Human periosteal cells were seeded on membrane pieces (collagen [Bio-Gides] and PRF) at a density of 104 cells/well. Cell vitality was assessed by fluorescein diacetate (FDA) and propidium iodide (PI) staining, biocompatibility with the lactate dehydrogenase (LDH) test and proliferation level with the MTT, WST and BrdU tests and scanning electron microscopy (SEM).

Results: PRF membranes showed slightly inferior biocompatibility, as shown by the LDH test. The metabolic activity measured by the MTT and WST tests was higher for PRF than for collagen (BioGides). The proliferation level as measured by the BrdU test (quantitative) and SEM examinations (qualitative) revealed higher values for PRF.

Conclusion: PRF appears to be superior to collagen (Bio-Gides) as a scaffold for human periosteal cell proliferation. PRF membranes are suitable for in vitro cultivation of periosteal cells for bone tissue engineering.

The rehabilitation of the severely resorbed posterior mandible remains a challenge. Even if many techniques of bone regeneration were tested with success in this area, they remain difficult surgeries and no consensus or standard have been raised yet. Because of the thick cortical bone of the mandible body, the alveolar bone regeneration or integration of a grafting material is often compromised. Moreover, the management of a regenerative compartment in this area is always difficult due to mechanical constraints and risk of soft tissue dehiscence. In this series of article, we developed and illustrated the concept of Screw-Guided Bone Regeneration (S-GBR), with excellent results in the posterior mandible. In this form of GBR, the barrier between the bone and gingival compartment is supported and protected through the presence of screws, serving both as tent pegs to maintain the regenerative chamber space and as bone growth pillars. Many combinations of bone materials and membranes are possible to get adequate results with various healing times, but the use of Leukocyte- and Platelet-Rich Fibrin (L-PRF) membranes as interposition, healing and maturation material became a common standard for us. L-PRF (Intra-Spin system and Xpression kit, Intra-Lock, Boca-Raton, FL, USA) is an optimized blood clot or membrane, which concentrates most of the platelets and half of the leukocytes of a blood sample. Through the release of growth factors and the effect of fibrin, this material promotes – among other effects – quick soft tissue healing and maturation and is considered as a form of barrier for Guided Bone Regeneration. In this article, we describe a modification of the S-GBR protocol termed Fast Screw- Guided Bone Regeneration (FS-GBR), where the severely resorbed posterior mandible was treated mostly with screws, allograft material and L-PRF membranes in order to reduce significantly the healing and regeneration times of the alveolar ridges.

Purpose: Purpose: To assess the relevance of simultaneous sinus-lift and implantation with leukocyte- and platelet-rich fibrin (L-PRF, Choukroun’s technique) as sole subsinus filling material.Materials: Twenty-three lateral sinus elevations (SA4 sinus) were performed on 20 patients with simultaneous implant placement. Seven patients were treated with 19 Astra implants (AstraTech, Mölndal, Sweden) and 13 patients with 33 Intra-Lock implants (Intra-Lock Ossean, Boca Raton, FL). L-PRF membranes were used to cover the Schneiderian membrane, the implant tips served as “tent pegs” for the L-PRF-patched sinus membranes, and the subsinus cavity was finally filled with L-PRF clots. Clinical and radiographic follow-up was performed just after implant placement, after 6 months, 1 year and each following year.Results: Six months after surgery, all implants were clinically stable during abutment tightening. The maximum follow-up was 6 years, and all patients were followed up for a minimum of 2 years. No implant was lost during this 6-year experience, and the vertical bone gain was always substantial, between 8.5 and 12 mm bone gain (10.4 ± 1.2). The final level of the new sinus floor was always in continuation with the implant apical end, and the periimplant crestal bone height was stable.Conclusion: The use of L-PRF as sole filling material during simultaneous sinus-lift and implantation seems to be a reliable surgical option promoting natural bone regeneration.

Synopsis
An implant-supported restoration of the maxillary anterior segment that is biologically, functionally, and esthetically acceptable following traumatic injuries in the maxillary anterior segment is always complex. Healing of the tissues is always difficult to control and the development of new techniques and materials to improve these treatments is still necessary. The use of platelet concentrates is an interesting approach. The objective of this technique is to gather platelet growth factors and to inject them on a surgical site to stimulate the healing process. Leukocyte and platelet-rich fibrin (L-PRF) allows for the preparation of strong fibrin membranes that are enriched with cells (activated platelets, leukocytes, circulating cells) and platelet growth factors. This autologous healing biomaterial is free of additives such as anticoagulants during blood harvesting or chemicals for activation. In addition, it is simple, inexpensive, and quick to prepare (15 minutes for all steps). The technique that is presented is specifically adapted to the practical needs in daily implant dentistry.This case letter documents the use of L-PRF during the replacement of a fractured central incisor with an immediate post-extraction implant and crown placement. As a strong solid fibrin membrane, L-PRF is seen to be particularly easy to use in implant dentistry and periodontology. In addition, it offers a protective effect (both mechanical and biological) to the grafted area.

Extensive bone grafting remains a delicate procedure, due to the slow and difficult integration of the grafted material into the physiological architecture. The recent use of platelet concentrates aims to improve this process of integration by accelerating bone and mucosal healing. Choukroun’s platelet-rich fibrin (PRF) is a healing biomaterial that concentrates in a single autologous fibrin membrane, most platelets, leukocytes, and cytokines from a 10-mL blood harvest, without artificial biochemical modification (no anticoagulant, no bovine thrombin). In this second part, we describe the implant and prosthetic phases of a complex maxillary rehabilitation, after preimplant bone grafting using allograft, Choukroun’s PRF membranes, and metronidazole. Twenty patients were treated using this new technique and followed up during 2.1 years (1–5 years). Finally, 184 dental implants were placed, including 54 classical screw implants (3I, Palm Beach Gardens, FL) and 130 implants with microthreaded collar (46 from AstraTech, Mo¨lndal, Sweden; 84 from Intra-Lock, Boca Raton, FL). No implant or graft was lost in this case series, confirming the validity of this reconstructive protocol. However, the number of implants used per maxillary rehabilitation was always higher with simple screw implants than with microthreaded implants, the latter presenting a stronger initial implant stability. Finally, during complex implant rehabilitations, PRF membranes are particularly helpful for periosteum healing and maturation. The thick peri-implant gingiva is related to several healing phases on a PRF membrane layer and could explain the low marginal bone loss observed in this series. Microthreaded collar and platformswitching concept even improved this result. Multiple healing on PRF membranes seems a new opportunity to improve the final esthetic result.

TRATAMIENTOS DE SUPERFICIE

Fractal patterns are frequently found in the Nature, but they are difficult to reproduce in artificial objects such as implantable materials. In this article, a definition of the concept of fractals for osseointegrated surfaces is suggested, based on the search for quasi self-similarity on at least 3 scales of investigation: microscale, nanoscale and atomic/crystal scale. Following this definition, the fractal dimension of some surfaces may be defined (illustrated here with Intra-Lock Ossean surface). However the biological effects of this architecture are still unknown and should be examined carefully in the future.

David Marcel Dohan Ehrenfest, DDS, MS, PhD1 University of Gothenburg, Department of Biomaterials, University of Gothenburg

Dental implants are commonly used in daily practice, however most surgeons do not really know the characteristics of these biomedical devices they are placing in their patients. The objective of this work is to describe the chemical and morphological characteristics of 14 implant surfaces available on the market, and to establish a simple and clear identification (ID) card for all of them, following the classification procedure developed in the Dohan Ehrenfest et al. (2010) Codification (DEC) system.
Fourteen different implant surfaces were characterized:
1. TiUnite,
2. Ospol,
3. Kohno,
4. Osseospeed,
5. Ankylos,
6. MTX,
7. Promote,
8. BTI Interna,
9. EVL,
10. Twinkon,
11. Ossean,
12. NanoTite,
13. SLActive,
14. Integra-CP.

Superficial chemical composition was analyzed using XPS/ESCA and the 100nm in-depth profile was established using AES. The microtopography was quantified using light interferometry (IFM). The general morphology and the nanotopography were evaluated using a FESEM. Finally, the characterization code of each surface was established using the DEC, and the main characteristics of each surface were summarized in a reader-friendly ID card. Results: FROM A CHEMICAL STANDPOINT, in the 14 different surfaces, 10 were based on a commercially pure titanium (grade 2 or 4), 3 on a titanium-aluminium alloy (grade 5 titanium), and the last one on a calcium phosphate core. 9 surfaces presented different forms of chemical impregnation or discontinuous coating of the titanium core, and 3 surfaces were covered with residual alumina blasting particles. 12 surfaces presented different degrees of inorganic pollutions, and 2 presented a severe organic pollution overcoat. Only 2 surfaces presented no pollution (Osseospeed and Ossean). FROM A MORPHOLOGICAL STANDPOINT, 2 surfaces were microporous (anodization) and 12 microrough, with different microtopographical aspects and values.10 surfaces were smooth on the nanoscale, and therefore presented no significant and repetitive nanostructures. 4 implants were nanomodified: 2 implants were nanorough (Osseospeed and Ossean), and 2 were covered with nanoparticles (NanoTite and SLActive). TiUnite and Kohno HRPS were covered with extended cracks all over the surface. Only 8 surfaces could be considered as homogeneous.This systematic approach allowed to gather the main characteristics of these commercially available products in a single ID card.

David Marcel Dohan Ehrenfest, DDS, MS, PhD1, Lydia Vazquez, Yeong-Joon Park, Gilberto Sammartino, and Jean-Pierre Bernard Chonnam National University School of Dentistry, LoB5 unit, School of Dentistry, Gwangju, South Korea

Background: Physical and bioceramic incorporation surface treatments at the nanometer scale showed higher means of bone-to-implant contact (BIC) and torque values compared with surface topography at the micrometer scale; however, the literature concerning the effect of nanometer scale parameters is sparse. Purpose: The aim of this study was to evaluate the influence of two different implant surfaces on the percentage bone-toimplant contact (BIC%) and bone osteocyte density in the human posterior maxilla after 2 months of unloaded healing. Materials and Methods: The implants utilized presented dual acid-etched (DAE) surface and a bioceramic molecular impregnated treatment (Ossean®, Intra-Lock International, Boca Raton, FL, USA) serving as control and test, respectively. Ten subjects (59 1 9 years of age) received two implants (one of each surface) during conventional implant surgery in the posterior maxilla. After the non-loaded period of 2 months, the implants and the surrounding tissue were removed by means of a trephine and were non-decalcified processed for ground sectioning and analysis of BIC%, bone density in threaded area (BA%), and osteocyte index (Oi). Results: Two DAE implants were found to be clinically unstable at time of retrieval. Histometric evaluation showed significantly higher BIC% and Oi for the test compared to the control surface (p < .05), and that BA% was not significantly different between groups.Wilcoxon matched pairs test was used to compare the differences of histomorphometric variables between implant surfaces. The significance test was conducted at a 5% level of significance. Conclusion: The histological data suggest that the bioceramic molecular impregnated surface-treated implants positively modulated bone healing at early implantation times compared to the DAE surface.

Among dental implant design alterations, surface modifications have been by far the most investigated topic. Regarding implant surface research, the lack of hierarchical approaches relating in vitro, in vivo, clinical trials, and ex vivo analyses has hindered biomaterials scientists with clear informed rationale guidelines for implant surface design. This manuscript provides a critical hierarchical overview of the in vitro, laboratory in vivo, clinical, and ex vivo methodologies used to investigate the performance of novel biomaterials aiming to allow dental professionals to better evaluate the past, present, and future dental implant surface research. This manuscript also contains an overview of the commercially available surface texture and chemistry modifications including novel nanotechnology-based fabrication processes. Over the last decade, surface texturing has been the most utilized parameter for increasing the host-to-implant response. Recently, dental implant surfaces utilizing reduced length scale physico/chemical features (atomic and nanometric) have shown the potential to synergistically use both texture and the inclusion of bioactive ceramic components on the surface. Although surface modifications have been shown to enhance osseointegration at early implantation times, information concerning its long-term benefit to peri-implant tissues is lacking due to the reduced number of controlled clinical trials. Given the various implants/surfaces under study, the clinician should ask, founded on the basic hierarchical approach described for the in vitro, laboratory in vivo data, as well as the results of clinical studies to effectiveness before use of any dental implant. ‘ 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 88B: 579–596, 2009

1 Department of Biomaterials and Biomimetics, New York University, New York, New York 100102 Department of Cellular and Molecular Biology, Fluminense Federal University, Niteroi, Rio de Janeiro, Brazil3 Department of Periodontology, Rochester University, Rochester, New York 146204 Department of Prosthodontics, Tufts University School of Dental Medicine, Boston, Massachusetts5 Department of Prosthodontics and Biomaterials, University of Alabama at Birmingham, Birmingham, Alabama 35294

Background: Surface modifications to dental implants have been used in an attempt to accelerate the osseointegration process. The objective of this study was to biomechanically/histomorphometrically evaluate a bioceramic grit-blasted and acid-etched surface (BGB/AA;test) versus a dual acid-etched implant surface (control) in a beagle dog model. Methods: Control and BGB/AA implants were subjected to a series of physicochemical characterization tools, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and auger photoelectron spectroscopy (APS). The animal model included the placement of 72 implants along the proximal tibiae of six beagle dogs, which remained in place for 2 or 4 weeks. After euthanization, half of the specimens were biomechanically tested (removal torque), and the other half was non-decalcified processed to slides of ;30 mm thickness for histomorphologic and histomorphometric (percentage of bone-to-implant contact [%BIC]) evaluation. Analysis of variance at the 95% confidence level and the Tukey post hoc test were used for multiple comparisons. Results: SEMand AFM showed that surface microtextures were qualitatively and quantitatively different and that the BGB/AA surface presented higher submicrometer average roughness values (Ra) and root mean square (RMS) values compared to control surfaces. Ca and P were detected at theBGB/AA surface by APS. Higher degrees of bone organization were observed along the perimeter of the BGB/AA surface compared to control, despite the non-significant differences in %BIC between the surfaces (P >0.25). Significantly higher removal torque was observed for the BGB/AA implants at both time periods (P <0.0001). Conclusion: According to the biomechanical and histomorphologic results, early biomechanical fixation was positively affected by the BGB/AA surface compared to the dual-acid etched surface.

Since the founding of the osseointegration concept, the characteristics of the interface between bone and implant, and possible ways to improve it, have been of particular interest in dental and orthopaedic implant research. Making use of standardized tools of analysis and terminology, we present here a standardized characterization code for osseointegrated implant surfaces. This code describes the chemical composition of the surface, that is, the core material, such as titanium, and its chemical or biochemical modification through impregnation or coating. This code also defines the physical surface features, at the micro- and nanoscale, such as microroughness, microporosity, nanoroughness, nanotubes, nanoparticles, nanopatterning and fractal architecture. This standardized classification system will allow to clarify unambiguously the identity of any given osseointegrated surface and help to identify the biological outcomes of each surface characteristic.

1 Department of Biomaterials, Institute for Clinical Sciences, The Sahlgrenska Academy at University of
Gothenburg, Sweden2 Department of Biomaterials and Biomimetics, New York University, New York, USA

Objective. The aim of this study was to evaluate the effect of surface treatment at the cervical region of endosseous dental implants on the alveolar bone remodeling after implantation immediately after tooth extraction in a dog model. Study design. The third and fourth premolars of 6 dogs were bilaterally extracted with a full-thickness flap, and threaded implants presenting a textured or a polished surface at the cervical regions were placed on the distal root extraction sockets. Submerged healing was allowed for 4 weeks, and bone-to-implant contact (BIC) and buccal and lingual bone loss were morphometrically measured. Results. The BIC and lingual bone loss were not significantly different between textured and polished groups. Significantly lower buccal bone loss (P _ .01) was observed for the textured surface at 4 weeks in vivo. Conclusion. Textured surface implants placed immediately after tooth extraction resulted in less bone loss only at the buccal cervical region compared with smooth surface implants. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;xx:xxx)

It is well established that, for several weeks following implant placement, the bone to implant bond is weaker as a result of the catabolic phase of bone. Strategies ranging from roughening the implant surface to applying osteoinductive materials have been employed in an attempt to re-engineer the bone response. A study was proposed to compare three different surface treatments. Implants of similar architecture from three manufacturers were evaluated to test early bone bonding. Tested were 36 endosseous implants with variations in surface treatment from three different manufacturers (12 of each type). One implant of each design was placed in each of 6 animals (beagle dogs), 3 per side in the mandible. The same protocol was used in the contralateral side two weeks later following the same distribution of the previous implant placement procedure. The animals were sacrificed 3 weeks after the initial implant surgery. For biomechanical testing, the bone blocks with implants were adapted to an electronic torque machine equipped with a 200 Ncm torque load cell. The implants were torque to interfacial fracture at a rate of ~ 0.19618 radians/sec, and the maximum torque value was recorded for each specimen. When compared to an acid-etched and particulate calcium phosphate coating (Nanotite? – Group 1) and a TiO blasted + HF etched surface (Osseospeed? – Group 2), at one week the Ossean? surface implants (acid etched and calcium phosphate impregnated – Group 3) had a 500% greater bone-bonding shear strength as demonstrated in a reverse torque pullout study. The conclusion reached is that there is a limitation of biologic activity on purely etched surfaces and there is also a qualitative difference in some nanotextured + calcium phosphate impregnated surfaces. The Ossean? surface appears to be biologically active in the sense that bone goes directly to the anabolic phase without intervening bone breakdown. This is relevant in immediate load cases and for extraction site defects where the percentage of initial bone-to-implant contact is compromised.

The objective of this study was to evaluate the biomechanical fixation of four different implant surfaces at early implantation times in vivo in a canine radius model. Methods: External hexagon Branemark type implants were utilized, and included the following surfaces: Microblasted (MI) (Ossean, Intra-Lock International), acid-etched and microblasted (AAM) (Nanoss, AMG), Anodized (A) (TiUnite, Nobel Biocare), and discrete crystalline deposition (DCD) (Nanotite, Biomet 3i) The implants were placed in the central region of the radii of 8 beagle dogs, remaining for 10 and 30 days in vivo. Following euthanisation, the implants were torqued to interface failure in a servoelectric system. Statistical analysis was performed at 95% confidence level by ANOVA considering Torque at dependent variables and implant surface and time in vivo as independent variables. Results: No significant differences between surfaces were observed in torque at 2 weeks in vivo. At 4 weeks, the AAM presented significantly higher torque values compared to the DCD and A surfaces (p< 0.001). The MI surface presented an intermediate value between the AAM, and the DCD and A surfaces. Significantly higher torque values were observed at 30 days compared to 10 days (p> 0.22). Conclusion: Significantly higher biomechanical fixation was observed for the AAM surface group when similar implant macrogeometries were utilized during mechanical testing.

The initial stability of dental implants is often times used as a predicament of its possible successful outcome. The purpose of this study was to evaluate the effect of different surface treatments and implant macrodesigns and on implant initial stability in a beagle model. Methods: The third and fourth mandibular premolars of adult beagle dogs (~1.5 years of age) were extracted and the sites allowed to heal for 8 weeks. Subsequently, different combinations of macrodesign and implant surface treatment in screw root form implant designs (31- Nanotite, Astra Tech-Osseospeed, Intra-Lock – Ossean) with similar diameter and length were placed following the suggested manufacturer’s surgical protocol. The implants remained for 1 and 3 weeks in vivo (n=6 per system and implantation time). Following euthanization, the mandibles were retrieved and the implants were torque tested to interface failure with custom tooling adapted in an automated machine. Statistical analysis was performed by one-way ANOVA at 95% level of significance and Tukey’s post-hoc test for multiple comparisons. Results: Significant differences were noted between groups following biomechanical testing (p<0.001; mean?95%Cl in Ncm; 1 week – 31 Nanotite= 19.43?8.39, Astra Osseospeed= 23.48?8.39, Intra-Lock Ossean= 107.6?8.39; 3 weeks – 31 Nanotite=25.17?10.27, Astra Osseospeed = 76.2?10.28, Intra-Lock Ossean = 94.82?10.27). Conclusion: The combination of macrodesign and surface treatment affected the initial stability of the implants.

Among the multiple factors that determine the achievement and the preservation of the osseointegration, physicochemical properties of the implant surface play a primary role Within milliseconds after exposure, an implant’s surface is covered with protein molecules absorbed from the surrounding environment. The nature, thickness, stability, and other characteristics of this protein layer depend in large measure on the characteristics of the surface. The structural details of the cells’ body that determine the achievement and preservation of a successful implant are the result of the stimuli that come from the implant surface. Keeping these considerations in mind, an evaluation of the adhesion and proliferation of the SaOs-2 Human Osteoblast on two comparative surfaces have been carried out over varying time periods. Phase 1: Superficial topographical characterization through X-ray Spectroscopy (XPS). Phase 2: Comparing Osteoblasts’ adhesion to the Ossean? surface Vs the Classic Blasted and acid etched surface. Phase 3: Comparing Alkaline Phosphatase (ALP) activity on those two surfaces has been closely evaluated of a various time periods. This enzyme is an early indicator of the osteoblastic differentiation. At the time the production of ALP on the part of human mesenchymal cells have been evaluated. These are capable of differentiating in at least three different phenotypes: the adipogenic, chondrogenic, and osteogenic line. It is however still not clear which factors determind the preferential differentiation towards a particular line. The objective of this research is try to understand if the surface per se’ and/or the presence of adequate chemical stimuli could induce the desired differentiation. Conclusion: The results of the research have demonstrated an advanced avtivity of the Alkaline Phosphatise Enzyme (ALP) on the Ossean? surface during the first days. The Ossean? surface shows, with statistically significant differential, a higher enzymatic activity compared to the Classic surface in the first phase of healing.

V. Bucci-Sabattini, C. Cassinelli, M. Morra Magenta, Italy.

2009, Academy of Osseointegration, Annual Meeting, CI-7

DISEÑO AUTORROSCANTE

Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs.Material and methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (901 cut at the apex, tap design); and (3) Blossomt (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 901 by a digital torque gauge. Controlled lateral loads of 10N followed by increments of 5 up to 100N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction.Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M _ standard deviation [SD]1/464.1 _ 26.8, 139.4 _ 17.2, and 205.23 _ 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (Po0.001) progressively from the Blossomt to the fluted to the non-fluted design (M _ SD1/4530 _ 57.7, 585.9 _ 82.4, and 782.33 _ 269.4 mm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossomt, fluted and non-fluted design groups, respectively.Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque.

Purpose: To evaluate the bone healing response to different implant root shape designs in a dog model. Materials and Methods: Three by eight millimeter screw-type short-pitch (SP) and large-pitch (LP) implants (Intra-Lock International, Boca Raton, FL, USA), and 4.5 ¥ 6 mm plateau (P) implants (Bicon LLC, Boston, MA, USA) were placed along the proximal tibia of six dogs for 2 and 4 weeks. The combination of implant design and final osteotomy drilling resulted in healing chambers for the LP and P implants. The implants were nondecalcified processed to plates of ~30-mm thickness and were evaluated by optical microscopy for healing patterns and bone-to-implant contact (BIC). One-way analysis of variance at 95% level of significance and Tukey’s test were utilized for multiple comparisons among the groups’ BIC. Results: Microscopy showed a ~150-mm region of newly deposited bone along the whole perimeter of SP implants, near the edge of the LP implant threads, and plateau tips for P implants. Rapid woven bone formation and filling was observed in regions where surgery and implant design resulted in healing chambers. No significant differences in BIC were observed (p > .75). Conclusions: Different implant design/surgical protocol resulted in varied bone healing patterns. However, the BIC and bone morphology evolution between implant designs were comparable. Regardless of the combination between implant design and final osteotomy drilling, bone morphology evolution from 2 to 4 weeks was comparable.

Purpose: This study tested the null hypothesis that differences in surgical instrumentation, macrogeometry, and surface treatment imposed by different implant systems do not affect early biomechanical fixation in a canine mandible model.Materials and Methods: The lower premolars of 6 beagle dogs were extracted and the ridges allowed to heal for 8 weeks. Thirty-six (n _ 12 each group) implants were bilaterally placed, remaining for 1 and 3 weeks in vivo. The implant groups were as follows: group 1, Ti-6Al-4V with a dual acid-etched surface with nanometer scale discrete crystalline deposition (Nanotite; Certain Biomet-3i, West Palm Springs, FL); group 2, Ti-6Al-4V with a titanium oxide-blasted fluoride-modified surface chemistry (Osseospeed 4.0 S; Astra Tech, Mölndal, Sweden); group 3: Ti-6Al-4V with a bioceramic microblasted surface (Ossean; Intra-Lock International, Boca Raton, FL). Following euthanasia, implants were torqued to interface failure and histologically evaluated. General linear modeling (ANOVA) at 95% level of significance was performed.Results: Histology showed that interfacial bone remodeling and initial woven bone formation were observed around all implant groups at 1 and 3 weeks. Torque values were significantly affected by time in vivo, implant group, and their interaction (P _ .016, P _ .001, and P _ .001, respectively). Regarding torque values, group 3, group 2, and group 1 ranked highest, intermediate, and lowest, respectively.Conclusion: Early biomechanical fixation at 1 and 3 weeks was affected by surgical instrumentation, macrogeometry, and surface treatment present for one of the implant systems tested. The null hypothesis was rejected.

Objective: to determine the in vitro insertion torque, and the early in vivo performance of self-tapping implant thread designs. Methods: The self-tapping implant thread designs were used: Blossom (B), Classic Cutting Flutes (DT), and no cutting classic design (C). All implants were 4mm diameter and 10mm length. The implants were inserted in a 3.2mm osteotomy in a foam material and the torque as a function of number of turns was recorded. For the in vivo part of the experiment, the implants were bilaterally placed in a 3.2mm osteotomy in the proximal tibia of 6 dogs, remaining for 2 and 4 weeks in vivo (6 per limb). Following euthanisation, half the implants were torqued to interface failure and the other half were nondecalcified processed for bone-to-implant contact determination. Statistical analysis was performed at 95% confidence level by ANOVA considering BIC and Torque as dependent variables. Results: The self-tapping implant designs presented lower insertion torque values compared to the C group. While up to 6 turns the B and DT implants presented similar torque vales, lower values were observed for the B values up to 12 turns. Time in vivo and implant design did not have an influence in torque to interface failure and BIC. Conclusion: While the self-tapping implants presented lower insertion torque values, no differences in BIC and torque to interface failures were detected between different implant tread designs at early implantation times.

IMPLANTES DE DIÁMETRO REDUCIDO

Abstract
Mini dental implants are becoming increasingly popular in dental care today. Because of their smaller size they are often used in cases of limited bone anatomy. Mini dental implants have diameters ranging from 1.8 mm to 3 mm and are suitable for long-term use. This article describes a retrospective analysis of 5640 mini dental implants placed into 1260 patients over a 12-year period. The mean length of follow-up was 3.5 years. The implants placed supported removable (2319) and fixed prostheses (3321), with placement in the maxilla (3134) and mandible (2506). The overall implant survival was 92.1%. Failures of implants (445) were attributed to mobility of the implant; the mean time to failure for these implants was 14.4 months. The small size of these implants has led to the development of techniques that enable placement and use in a short amount of time for both the doctor and patient. The high rates of success show that mini dental implants are suitable for use in supporting fixed and removable prosthetics.

Dental mini implants were first introduced as transitional implants to support interim prostheses during the healing of a definitive implant or implants. When the inter-radicular space and/or buccolingual bone width are limited, however, mini-implants have been used successfully as definitive implants. This article describes in detail the use of a miniimplant in the treatment of a congenital missing maxillary lateral incisor. Also discussed are recommendations for mini-implant placement relative to anatomic landmarks as well as the surgical and prosthetic rationale.

Learning Objectives: This article highlights the surgical and prosthetic considerations used in mini-implant placement for a patient with a congenitally missing lateral incisor. Upon completing this exercise the reader should:

• Understand the clinical indications for successful use of mini-implants.

• Improve his or her clinical decision making relative to the selection of miniimplants versus conventional implants.

DISEÑO DE LOS ADITAMENTOS

This study sought to evaluate the sealing capability of the implant abutment connection of different dental implant systems. Five Nobel Replace select, Straumann and Intra-lock implants of approximately 4Æ5 mm diameter with their respective abutments were provided by the manufacturers. A calibration curve was determined by placing toluidine blue (TB) increments of 0Æ1 lL into 1Æ5 mL of distilled water and recording its absorbance in a spectrophotometer until reaching 0Æ7 lL. Then, 0Æ7 lL of TB was placed in the deepest portion of each implant’s internal screw, the abutments were adapted to the implant according to the manufacturer’s instructions and the specimens were placed in vials with 1Æ5 mL of distilled water. Spectrophotometric analysis was performed at 1, 3, 6, 24, 48, 72, 96 and 144 h. Statistical analysis was performed by One-way ANOVA at 95% level of significance. The calibration curve was linear with respect to the TB amount in 1Æ5 lL distilled water (R2 = 0Æ9961). All implant abutment systems presented an increase in absorbance as a function of time. As time elapsed in vitro, significantly higher amounts of TB was released from the Straumann and Nobel Replace Select connection systems (P < 0Æ0001). Leakage was significant between the groups. Despite controlled torquing, the seal between the implant body and the abutment could not be maintained in all three of the systems tested.

*Department of Biomaterials and Biomimetics, New York University, New York, NY, †Department of
Prosthodontics and Operative Dentistry, Tufts School of Dental Medicine, Boston, MA, ‡Departments of Dentistry & Otolaryngology, Montefiore Medical Center / Albert Einstein College of Medicine, Bronx, NY and §Department of Periodontology, University of Rochester School of Dentistry and Medicine, Rochester, NY, USA